In order to enhance the recovery of scrap metal contaminated with combustible hydrocarbons, it is desirable to remove the contaminants prior to melting the scrap metal. It has been recognized that organic contaminants such as paint and lacquer, which are presently coated on aluminum beverage cans, have heat content which can be recovered to heat incoming material. The use of the heat content of hydrocarbon contaminants has been used in drying and oxidizing operations. Three patents which teach the usefulness of preheating with burned hydrocarbons are U.S. Pat. Nos. 2,795,054: 3,005,699; and 3,623,235. In addition, a method of using vaporized fumes to preheat material in a rotary kiln is taught in U.S. Pat. Nos. 4,548,651 and 4,601,750.
U.S. Ser. No. 879,066, entitled "Process and Apparatus for Removing Volatiles from Metal" which was filed June 26, 1986, and assigned to Aluminum Company of America, teaches a process and an apparatus for removing volatiles from metal, especially aluminum, without the step of vibrating the material as it is transported through a furnace. Such a process and apparatus is highly efficient, relatively pollution free, easily operated and capable of handling large quantities of scrap metal. However, it has been found that a more efficient operation can be obtained by vibrating and fluidizing the material being transported on the conveyor through a furnace.
Now a process and an apparatus have been invented which includes the step of vibrating and fluidizing the metal to maximize the contact between the surface of the metal and the recirculating gas within the furnace to vaporize substantially all the volatiles contained thereon.